The present invention relates to an arrangement for the processing of a sealing fin on a packing container. More specifically, the present invention relates to an arrangement for the processing of a sealing fin of a packing container, the arrangement having two co-operating processing jaws, carrier elements for the jaws and driving elements.
In packing machines of the type which produce and fill so-called ridge or gable-top packages from preformed laminated blanks, a sealing together and shaping of the ridgelike upper part of the packing container takes place after the filling. In the sealing together of the sealing panels of the top, the thermoplastic surface layers of the packing laminate are made use of as an adhesive. The packing containers therefore pass through activating and preforming stations wherein the sealing panels are heated so that the thermoplastic layers melt and the packing top is mechanically preformed to practically the final ridge shape. Then a compression and sealing of the upper sealing panels which are to form the sealing fin of the top is achieved by co-operating processing jaws which from opposite sides press together and cool the sealing panels so that the thermoplastic layers are combined and a tight and true seal is obtained. A known machine operating in this manner is described e.g. in Swedish Pat. No. 361857.
The final processing or sealing together of the sealing fin of the top is achieved in types of machine known up to now as mentioned previously by co-operating processing jaws which in the inactive position are at a distance from one another and permit the introduction of the prepared packing top between them. The packing container is brought into the correct processing position with the help of a conveyor which is situated in relation to the processing jaws so that the top fin is placed directly adjoining the one, fixed or possibly spring-suspended processing jaw. Subsequently the other, driven processing jaw is activated so that it is moved by driving elements to the active position in contact with the sealing fin when the compression of the latter takes place. Since only the one processing jaw is directly drivable, a certain lateral displacement of the sealing fin in connection with the sealing is unavoidable because of the tolerances. This is undesirable, since it may cause a deformation of the top giving rise to defective sealing and leakage as a consequence.
It has been endeavoured to overcome these difficulties by altering the tolerances, spring suspensions or the like. However this involves a costlier design and requires more maintenance which is inappropriate in packing machines with exacting, continuous operation.
It is an object of the present invention, therefore, to provide a packing machine which has a top compression station without the aforementioned disadvantages.
It is a further object of the present invention to provide an arrangement for top compression which is of a simple design and contains few movable parts wherein play and faults can arise.
It is a further object of the present invention to provide a top compression arrangement which operates simply and accurately and which can be manufactured at low costs.
These and other objects have been achieved in accordance with the invention in an arrangement for processing of a sealing fin on a packing container. The arrangement includes two mutually co-operating processing jaws, carrier elements for the jaws and driving elements. Each processing jaw is supported by a carrier element movable in relation to the machine frame, which via spring devices is movable reciprocally in relation to the carrier element of the opposite jaw between an active position wherein the processing jaws are in contact with the sealing fin and an inactive position at a distance from the sealing fin.
The arrangement in accordance with the invention is flexible and easy to maneuver by virtue of its design and at the same time can operate with high precision. This has been achieved through the unconventional solution of using spring-suspended carrier elements for the processing jaws. The driving of both jaws increases the precision and reduces the risk of defective sealing at the same time as the small number of movable parts substantially increases operational reliability and precision.